A variety of unified floor assemblies, incorporating varying amounts of wood and steel and suitable for specific purposes, are known. These include manufactured unified floor assemblies, of a type readily towed on public highways to a selected site for use, as taught in my patents U.S. Pat. Nos. 4,930,809, 5,028,072, and 5,201,546.
The goal is to provide an economically-manufactured, strong but light, conveniently transportable floor assembly which can be cooperatively mounted on site with one or more other similar floor assemblies as part of a building structure. There are numerous advantages in manufacturing floor assemblies in this manner, including uniform quality control, economies of scale in manufacture, optimum utilization of skilled and trained manpower, and the facility for precisely customizing product to suit the needs of individual customers. The use of lengthwise steel beams in such floor assemblies provide strength but may add to the weight and costs more than wood. It is therefore desirable to minimize the use of steel in such floor assemblies. This is best accomplished by judiciously combining wood and steel.
One increasingly common use for such manufactured floor assemblies is in forming the ground level floors of building structures that have basements. It is not uncommon nowadays to have each floor assembly of fairly large size, e.g., such as to provide a useful floor area of the order of 14 ft..times.40 ft. or longer. The resulting floor structures typically are supported either on upright basement walls or on metal or masonry posts disposed where two immediately adjacent floor assemblies come together and are connected to provide a large continuous useful floor.
Such floor assemblies typically provide a floor at an upper surface and also a lower surface which can inherently serve as a ceiling for the basement portion of the finished structure. As in all floors, there is in such floor assemblies a vertical spacing between the uppermost horizontal surface which serves as the floor for the space above the floor assembly and the lowermost horizontal surface which usually serves as the ceiling for the basement portion of the finished structure. By suitable selection of the dimensions of this space it becomes possible during the process of manufacturing the floor assembly to include ventilation ducting, piping, electrical power telephone lines, wiring, and the like, for easy connection to sources of warm or cold air, hot or cold water, and the usual electrical power and telephone lines from outside, respectively.
Uniformity of the finished product and high quality control are readily realized where the manufacturing of the floor assembly and its innards takes place under a roof rather than in the open as is common in forming floor structures on site in the open and when exposed to inclement weather conditions.
As noted, for different needs it is desirable to have particularized structural features. One such need is for a floor assembly having a precisely-dimensioned preformed opening for the location of a stairway. As persons of ordinary skill in the art will appreciate, the formation of such a hole in a floor assembly of conventional type can generate a structural weakness which can become a serious problem when the manufactured floor assembly is towed at typical highway speeds over uneven road surfaces. Such an opening must therefore be properly reinforced when the floor assembly is manufactured, i.e., before it is towed away.
There is, therefore, a clear need for a lightweight, reasonably priced, modular floor assembly which allows an architectural designer to specify an opening for a stairway leading downwardly from the floor on site. The present invention is particularly suited to meet this need.